The use of communication systems having wireless mobile communication units has become widespread. Wireless communication systems that operate within a cell or coverage area provide several important advantages over conventional wired systems. For example, wireless communication users can communicate in locations where wired service is not available or feasible, such as remote or rugged locations. Additionally, wireless communication users within the cell have much more mobility because the units do not have to be connected to a fixed wired network. These and other favorable characteristics make wireless communications ideally suited for personal, business, military, search and rescue, law enforcement, water vehicle, and other field related applications.
If an area is equipped with robust communications infrastructures (e.g., cell towers), there are relatively easy ways to establish and maintain such wireless communications to mobile users, by making use of the infrastructure. However, there are some endeavors where it is necessary to provide such a wireless communications capability even while in an area that does not have such a communications infrastructure, and in such cases it is much more difficult to establish and maintain such wireless communications to mobile users.
Even in areas without such a robust wireless communications infrastructure, there are techniques that have been developed to enable the mobile members of a team to establish and maintain digital communications. For example, it has become increasingly common to provide wireless communication devices in motor vehicles. The interior of a motor vehicle provides a relatively controlled environment for such a device to operate, and the motor vehicle itself generally provides a large antenna mount and, more importantly, a ready source of power. This has allowed vehicles to incorporate a number of useful functions, including automated incident notification, two-way audio communication, and even limited information retrieval, such as sporting event results and stock reports. Several successful implementations in the military sphere have been based on netted line-of-sight radios, and netted line-of-sight radios combined with satellite data terminals designed for mobile operations.
While vehicle mounted wireless communications systems offer many convenient features, they are disadvantageous in that they require the operator to remain within the vehicle to be useful. Often, the very time where a wireless device would be most useful is a situation where a motor vehicle has become damaged or inoperative. In such a case, it may become hazardous for an operator to remain within the vehicle to make use of the communications system. Similarly, situations may arise where an occupant must leave the vehicle for another reason. For these situations, a dismount solution would be desirable that maintains much of the functionality of the vehicle communications system while maintaining a minimal size and weight.
Presently, the functionality of dismount devices is limited by a number of considerations. Increased functionality requires an increased number of components increasing the size, weight, and power consumption of the dismount device. These considerations are aggravated by the redundancy of the dismount device in the context of a vehicle communications system, as the dismount device is necessary only on those infrequent occasions where the operator requires wireless communications while separated from the vehicle.
In military applications, existing communications systems to and from individuals separated from a vehicle (referred to as dismounted users), however, have suffered from severe technical limitations that impede and degrade tactical operations in significant ways. Existing problem areas include battery life, range, relaying, safety, weight, complexity of operation, setup and configuration time, and missing functionality. Similar problems plague electronic communications to small mobile teams in other domains, such as search-and-rescue teams, and law enforcement agents in the field.
Most of these problem areas can be related to the issue of battery life; the severe limitations on battery capacity limit the transmit power, which in turn limits communications range. The same severe limitations on battery capacity also limit the transmit duty cycle (i.e., the duration or percentage of time which a transmitter can be on and transmitting), preventing a dismounted individual from communicating continuously without either receiving new batteries or having access to a battery charger for appropriate mission durations. Current implementations are so inefficient that to carry spare batteries for an entire week's worth of mission would be infeasible.